19 Minibuffers

A minibuffer is a special buffer that Emacs commands use to
read arguments more complicated than the single numeric prefix
argument. These arguments include file names, buffer names, and
command names (as in M-x). The minibuffer is displayed on the
bottom line of the frame, in the same place as the echo area
(see The Echo Area), but only while it is in use for reading an
argument.